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Old 05-03-2001, 09:38 PM
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Join Date: Jan 2001
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During today's oil change, I removed the filter (Hengst) and found that the metal portion of the filter had dramatically collapsed inwardly. The paper portion appeared normal. I called the Mercedes shop and asked if they may know may have caused this, but they did not know. I use 15W-40 oil, same as usual.

I remember someone mentioned that on the oil filter top there is a hole in the stem. Is this a valve that only works in one direction or just a drain hole? When I put some air through the hole, it is not clogged up.

Has anyone had this happen before? The Mercedes shop says put a new filter on, watch the oil pressure, and check the filter in a week.

Any help would be appreciated.... Joe

Mercedes 1984
300D Turbo
155,600 miles

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Old 05-03-2001, 10:54 PM
SW SW is offline
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Location: Houston, TX. USA
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I've never experienced this before. Oil should flow into the small hole at the top and out the bore of the stem. Yes, there is a check valve in the bore of the stem.
2001 Dodge Ram 2500 Cummins Turbo Diesel - 4x4, auto, 3.54 gears, long bed
'92 300D 2.5 Turbodiesel - sold
'83 300D Turbodiesel - 4 speed manual/2.88 diff - sold
'87 300D Turbodiesel - sold
'82 300D Turbodiesel - sold
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Old 05-04-2001, 10:29 AM
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Posts: 29

If there is a check valve within the oil housing cap tube, does this mean that compressed air (or oil) will only flow in one direction?

When I put air into the stem, it exits through the oil port hole, likewise when I put air through the oil port hole it exits through the stem. If there is a valve, what does it consist of? Could this be the cause of my oil filter collapsing?

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Old 05-05-2001, 05:48 PM
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Location: Cincinnati, Ohio
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That's why it pays to use a good quality filter, as you did. Companies like Hengst and Mann will cover the cost of any repairs of damage caused to an engine due to the defect of one of their products. So just put a new filter in, watch the engine carefully for any signs that something's amiss, and let us know!
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Old 05-13-2001, 08:34 PM
jrd jrd is offline
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Location: Oakland, CA
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What's the best way to clean the filter stem? I couldn't blow air through it last time I changed the oil. What is the function of this cavity?

Justin Dobbs
Oakland, CA
1987 300D Turbo 201k
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Old 05-03-2002, 09:09 PM
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Location: Tucson, Arizona
Posts: 758
Same problem this oil change

Greetings Joe,

Just wondering if you ever resolved your collapsed oil filter problem? I used the same filter on my car and ran it about 3900 miles before I just changed the oil tonight and the filter was collapsed equally all around the exterior upper metal housing. I suppose that's what yours did. I can't imagine what the problem to be as this is the first time this has happened. Ever found out what caused yours to do this? I installed a Mann filter this time. I'd done some higher speed driving this time around, 70-75 mph but hat shouldn't cause it. Any ideas?

"Tell me and I will listen, Teach me and I will learn, Show me and I will accomplish, Involve me and I will succeed."
'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan
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Old 05-04-2002, 07:14 PM
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Filter Collapse


Thanks for asking. A few months ago I took my car to the Mercedes Shop and they found nothing mechanically wrong. After they examined the filter they told me try using a Knecht filter and I have not had any trouble since. The metal portion of the Knecht filter seems a little heavier thickness of metal and seems (for now) to be working okay.


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Old 05-04-2002, 11:39 PM
Posts: n/a
I've been using fram filters for years. I've never had any problems with thme collapsing. I change my oil every 3000 miles and never have any problems like that. Has anyone ever had any problems with fram? The reason I use them is that they are locally available in the local parts store. They seem to work well.
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Old 05-05-2002, 12:01 AM
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My local parts store only carries Fram filters. I went out to the garage to see if I had any more to try and get a part # but, no more. I've never used another type of filter. If the concensus here is to use OEM brands then I will switch. I don't want to harm my motor. Off the topic a little, is there a thermostat for the oil cooler? And if so, does it need to be changed periodically? I'm only curious. I am not having any problems with it. I just want to know because when we do oil coolers at the track there are usually thermostats so the oil doesn't get too cold. IT DOES HAPPEN! Again, just curious.
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Old 05-05-2002, 12:57 AM
Join Date: Nov 2001
Location: Cape Cod Massachusetts
Posts: 1,427
Question Collapsing Filter = Failed Check Valve?

The upper portion of the filter is the by-pass portion of the filter that has a much finer filter media. The under pressure the a small portion of the unclean oil is forced through the cannister holes, through the filter media, into the small hole on the filter cover stem, down the stem, past a check valve, and into the oil pan. It would seem that the size of the hole in the stem is the factor that normally determines how much oil moves through the by-pass filter element at any given pressure. If the stem hole, stem, or the check valve in the stem where blocked, the oil under presure would have no effect on the filter cannister.

It would seem that if the small cannister holes became restricted, perhaps a simple over-loading or clogging of the filter media just inside the cannister holes, maybe from dirtier oil from driving harder than usual, a situation would occur where the perforated metal canister in combination with restricted holes/media would be the barrier directly acted upon by the dirty oil under presure and as long as the stem hole/stem/check vale remained functioning, the upper cannister metal portion could be collapsed inward towards the stem.

It might also be that if the oil cover stem check valve has failed there could be a condition that would exist where the normal check valve resistance is absent and the lessening of the designed oil flow restriction ( from the functioning check valve spring pressure) would contribute to a greater force than normal being applied to the cannister/filter media barrier from it's outside collapsing it inward towards the stem. At the same time if the oil flow through the by-pass filter increased in volume due to a decreased restriction (again, from a failed check valve ) it would stand to reason that the filter media just inside of the cannister holes might get clogged more quickly.

So the failure of the check valve to provide the resistance as designed would be allowing a greater flow of dirty oil initially that could be clogging the filter media/opening prematurely creating a pressure barrier that is acted upon by the unfiltered oil under pressure collapsing the upper portion of the cannister.

When I change the oil on my 603 engine I usually use air applied to the stem hole to blow the stem clean and then I put a squirt of WD-40 or similar product into the stem hole, let it sit for a couple of minutes and then blow that out, usually two or maybe three times. I don't know what the design spec is for the stem check valve but I'm sure it at least a couple of PSI the way it releases (yeah the garage wall will forever show evidence of the first time I did this without having the stem end INSIDE of a suitable rag!). I can't imagine that you should be able to create a flow in reverse if the check vale was operateing as designed. So perhaps if the check valve is absolutely not fuctioning that could be the root cause of the filter collapse.

There also appears to be a couple of pressure releif bypass valves in the oil system, a 7 Bar at the oil pump and a 3.5 Bar in the filter housing I suppose if one of these failed to operate as designed an over pressure/flow condition could exist that might overtax the cannister/filter media and lead to a collapse due to an over pressurization state?

Last edited by Billybob; 05-05-2002 at 01:06 AM.
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Old 05-05-2002, 03:09 AM
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Location: Pacifica (SF Bay Area), CA
Posts: 2,946
Thumbs down Fram filters

STAY AWAY FROM FRAM!!! My auto shop teacher back in high school had a Fram filter, along with an AC Delco and an Amsoil filter. The Fram had very little filter paper compared to the AC filter. It was laughable. Prior to that I had been using Fram as it seemed to be the most readily available...since then I've been mainly going to the dealer for my filters (Ford Motorcraft in my case, so far). I've also heard of Fram paper elements coming apart in diesel oil and doing engine damage, although I'm not 100% sure that's completely true...still, IMHO, it's cheap insurance to go for a better version...OEM would be ideal, of course.

Just my $.02...good luck!
2001 VW Jetta TDI, 5 speed, daily driver
1991 Ford F-350, work in progress
1984 Ford F-250 4x4, 6.9l turbo diesel, 5 speed manual
Previous oilburners: 1980 IH Scout, 1984 E-350, 1985 M-B 300D, 1979 M-B 300SD, 1983 M-B 300D
Spark-free since 1999
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Old 05-05-2002, 12:18 PM
Join Date: Nov 2001
Location: Cape Cod Massachusetts
Posts: 1,427
Lightbulb Art!

Yeah Bill, it is sort of Jackson Pollackish!

Especially because in this "piece" my technique was developed from my immediate reaction, which was to simultaneously refrain from the automatic expletive and to instinctively grab the nearby rag and wipe! So it's an intriguing combination of freeform high velocity spattering with a desperate wipe slashing across the middle of the space! I suppose it is in some way an organic interpretation of a man's instinctive response to be in his own small ways, effecting the disordered cosmic chaos that is!

Officially untitled, but I'm certain my wife would find some pleasure in calling it something like " Stupid Man, Angry Wife!"

An because its on the interior wall I guess I should consider myself lucky that it remains a part of my "Private Collection" rather than for my vast public audience's consumption!
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Old 01-22-2003, 11:51 AM
Posts: n/a
Oil Filter Bolt Port holes - how to clean?

I have a 1995 E300 Diesel...& am unsure how to clean those port holes/channel on the Oil Filter Bolt(tube) that is supposedly easily cleanable with compressed air.

Ive searched the discussions, am unable to find anything real helpful.

There is a real slow oil sludge that flows out of the bottom of the port hole when I hold this Oil Filter bolt upright, I am unable to clean those holes or channel - they stay dark colored & seem about 90% clogged.

I tried blowing air thru the top hole down the bottom port hole with a bicycle pump, also by my mouth(with assistance of clean rag) but was unable to blow any air thru.

Maybe I should shoot WD-40 down the top hole, maybe run hot water thru the top hole for 20 minutes or so, maybe take this thing to Sears & borrow their compressed air, maybe try shooting gunk oil cleaner & soaking the tube in that stuff overnight, Im open to suggestions
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Old 01-22-2003, 12:06 PM
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Posts: 29
Cleaning oil filter tube

Try using a small can of compressed air and a small plastic tube that can be attached to the nozzle.

For example, I am looking at a product manufactured by "Endust for Electronics" that comes in a 10 oz metal can and includes a red plastic tube for narrow spaces. I believe it can be bought at most stores in probable the computer department since it can be used for cleaning computers, keyboards, televisions, and so forth.

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